U.S. President Donald Trump has ordered the establishment of a space command that will oversee the country's military operations in space.

Trump signed the one-page memorandum on December 18 directing the Department of Defense to create the new command to oversee and organize space operations, accelerate technical advances, and find more effective ways to defend U.S. assets in space, including satellites.

The move comes amid growing concerns that China and Russia are working on ways to disrupt, disable, or even destroy satellites on which U.S. forces rely for navigation, communications, and surveillance.

The new command is separate from Trump's goal to create an independent space force, but could be a step in that direction.

Speaking at the Kennedy Space Center in Florida, Vice President Mike Pence said: 'A new era of American national security in space begins today.'

Space Command will integrate space capabilities across all branches of the military, Pence said, adding that it will develop the space doctrine, tactics, techniques, and procedures that will enable our war fighters to defend our nation in this new era.'

It will be the Pentagon's 11th combatant command, along with well-known commands such as Central Command and Europe Command.

Space Command will pull about 600 staff from existing military space offices, and then add at least another 1,000 over the coming years, the Associated Press quoted an unidentified U.S. official as saying.